The spaceborne ESA-mission CHRIS-Proba (Compact High Resolution Imaging Spectrometer-Project for On-Board Autonomy) provides hyperspectral and multi-directional data of selected targets spread over the world. While the spectral information content of CHRIS/Proba data is able to assess the biochemistry of a vegetation canopy, the directional information can describe the structure of an observed canopy. In this study we proposed to demonstrate the effects of changing background on the hemispherical-directional reflectance factor (HDRF) of a coniferous forest based on a multi-temporal CHRIS-Proba data set (summer / winter scene) over the Swiss National Park. However, the data status of the CHRIS-Proba observations did only allow for an appropriate pre-processing of the summer scene. Instead the complex 3-D radiative transfer model FLIGHT was employed to assess the influence of changing background (understory vs. snow) within a forest canopy. The study shows the enhanced potential of the directional and spectral information content of CHRIS/Proba for mapping heterogeneous canopies using a multi-temporal data set.